Stabilization of dichlorobutadiene resins



Patented Jan. 9, 1951 UNITED STATES, PATENT OFFICE STABIL Z ON-F m RESI s Eugene P. Stefl, Cuyahoga Falls; andLloyd-O. Bentz, Akron, Ohio, assignors to The Firestone Tire & Rubber Company, Akron, Ohio, a cor poration of ,Ohio

CHLOROBUTADIENE' N N 0 Drawing. Application July '19, 1949, Serial'No. 105,672

4 Claims,

This invention relates to the stabilization,

against discoloration and other deterioration bylight and oxidation, of resinous polymers andcopolymers of 2,3-dichloro-1,3-butadiene, hereinafter referred to, forbrevity, as dichlorobutadieneff In general, the invention is based upon the discovery that the resistance to light Ofthese polymers and copolymers may be greatly en hanced by the addition thereto of the reaction product of a bisphenol-A and salicyclic acid produced under esterifying conditions.

THE DICHLOROBUTADIENE' RESIN S 2,514,195) that the intractable nature-of the. earlier dichlorobutadiene polymers is due to their;

excessive molecular weights and to a slight cross:-

linking which becomes significant at such high" molecular weights. It has further been discovered' (Kuhn 2,514,195) that, providing the'polymers-of dichlorobutadiene are preparedin-such a manner that their molecular weight corresponds to an intrinsic viscosity offrom 0.1- to1.5;

the polymers are fusible toyieldfluidmelts;are soluble in hot solvents andhave crystalline prop- 2 of polymer. This degree of chlorination .doesnot appear to alter the essential-polymeric chain, but merely breaks up excessively long-molecules, and

the cross-linkages and side-structure attendant thereon.

2. The use of -modifying agents, as the-term is eused in. the synthetic rubber industry,.to include certain polymerization:controlling sub stances such as lauryl mercaptan,;buty1mercap tan, thiophenols, hexamethylenedimercaptan, di-

isopropyl xanthogen disulfide; The inclusion,- the'polymerization mass, of from oj to 3.0%, or in the case of someof; the less powerfulmodifiers, as highas of these -modifier s, basedon the weight-pf monomers (including -;comonomers as -;detai1e.d below)- wi-lhdevelop highly crystalline erties similar to those of the nylon and. vinyl1 dene chloride resinsi. e., they may be extruded and cold-stretched to yield filaments, cordage etc., having excellent strength and flexibility and exhibiting oriented-crystalline X-ray patterns; These latter resins are clearly of great technical merit, and accordingly the invention is more particularly directed to thestabilization of such crystalline resins. However, it isto be understood that any polymersor copolymers of dichlorobutadiene (Whether or not crystalline as .above described) containing a sufiicient amount of dichlorobutadiene .(say from about 25% to 100% based .on the total weight of resin) so that failure thereof -.under exposure'to light occursby mechanismsinvolving the polydichlorobutadiene structure, may be stabilized in accordance with this invention.

Some techniques which have been found to yield polymers of;di c hlorobutad-i trinsic viscosityrangeof fromRO. 5to:1 .5;are:

1. A restrained chlorination of any'infusible polymer or copolymer of dichlorobutadiene prepared in accordance-With the prior art, the chlorine uptake beingstrictly confined to the range .2-10.%.,-an pre e ab y s nthe weigh propertiesin the resultant; resins. This technique is applicable to solution; emulsion or mass polymerization. Recommended amounts ofthe var-- ious types of I modifiers are asfollows.

Table I Amount to beused (per ceglllt, basgefit on ewel Type of Modifier or dichlofo; butadiene in polymerization mass) Aryl'mercaptans (containing SH-groupsdirectly attached to aromatic nuclei) 0.05 to 2.0 Aliphatic, cycloaliphatic, and araliphatic mercaptans (containing froinl to 8 carbon atoms) 5 .to 5. 0 Aliphatic, cyloaliphatic and araliphatic mcrcaptans' (containing from 91to 20ca1fb'on atoms)' 2 to 15 3. Polymerization-in non-reacting organic solvents e. g.. toluene, benzene, methanol; ethanol,-

ether, hexane, etc," in-concentrations from about 10% to about-%, based on the total Weight of solvent and dichlorobutadiene, at relatively elevated temperatures on the order-of from about 40 to about Q., an'd in the presence of from about 0.1% to 5.0%, based on the total weight of polymerization 'mass, of a peroxidic catalyst such as -benzoyl --peroxide.

4.- Polym erizing ,dichlorobutadiene or mixtures thereof with copolymerizable compounds insolution in organic solvents at'temperatures in excess of -C., in the presence of inhibitors such as p-cresol employed to the extent of about 1%, based on the-weight of dichlorobutadiene.

Of all of these techniques, that outlined under (2) is the most practical and reliable for the mall As noted above, the present invention may be applied to the stabilization of both of homopoly: mers of dichlorobutadiene and of copolymers thereof with unsaturated compounds eopo ly- 'merizable therewith. Dichlorobutadiene readily copolymerizable with a wide variety of unsaturated compounds which are themselves additionpolymerizable; and the stability of the resultant resins is materially enhanced by the addition of bisphenol-A salicylic acid adducts in accordance with this invention, provided that the dichloro bu'tadiene is present to an extent (say 25% to 100%, based on the weight of resin) such that the mechanism of degradation thereof contributes substantially to the ultimate failure of the resin. It is understood that, if the resin is to be of the fusible, crystalline type, it must not contain more than about 2% of a crosslinking comonomer (i. e., a plurality unsaturated comonomer in which the ethylenic groups are not conjugated or cross-conjugated) nor more than about -15% of any other comonomer. These last two restrictions do not apply, if fusible, crystalline resins are not desired. Suitable non-crosslinking comonomers are exemplified in vinyl compounds on the order of vinyl chloride, vinyl acetate, vinyl ethyl ether, vinyl c-chloroethyl ether, vinyl higher fatty ethers, vinyl phenyl ether, etc.; vinyl ketones such as vinyl methyl ketone, methyl isopropenyl ketone, vinyl phenyl ketone, etc., cyclic vinyl compounds such as styrene, c-methyl styrene, nuclearly chlorinated styrenes, p-vinyl benzoic acid, p-vinyl naphthalene, vinyl benzoate, vinyl carbazole, various vinyl pyridines, and the like; acrylic and substituted acrylic compounds such as methyl acrylate, methyl methacrylate, vinyl furane, ethyl chloroacrylate, methacrylonitrile, chloroacrylonitrile, acrylonitrile and the like; vinylidene halides such as vinylidene chloride, vinylidene bromide, 1-fiuoro-1-chloroethylene; 1,1-dichloro-2,2-difluoro-ethylene; compounds bearing an active cyclic unsaturated carbon atom such as coumarone, indene, i-methylene-LB-dioxolane, substituted derivatives of this material, and the like. Examples of suitable conjugated and cross-conjugated copolymerizable compounds are butadiene, cyclopentadiene, chloroprene, l-chlorobutadiene, isoprene, 2,3-dimethyl butadiene-1,3-piperylene, 2 methyl pentadiene, etc.

THE REACTION PRODUCT OF BISPHENOL-A AND SALICYLIG ACID The reaction product of bisphenol-A and salieylic acid employed in this invention is produced by reacting together bisphenol-A, which is a known compound having the structure and disalicylates of bisphenol-A having the respective formulae:

I OH CH:

and

The reaction product is produced by reacting one mole of bisphenol-A with from 2 to 3 moles of salicylic acid under esterifying conditions. The esterifying conditions may be any ordinarily used for effectingesterification of aromatic acids and phenolic compounds and the reaction may be promoted by the presence of acid catalysts such as phosphorus oxychloride, sulfuric acid, anhydrous hydrogen chloride and the like. The esterification may be carried out over a wide range of temperatures, e. g. in the range 50-200 C., and in the presence of inert solvents such as benzene, toluene, xylene and the like. The reaction is carried out to such an extent as to abstract between 1.5 and 2.0 moles of water for each mole of bisphenol-A employed.

Coming now to the amount of the bisphenol-A salicylic acid reaction product to be added to the dichlorobutadiene resin, as little as 0.5% of this material, based on the weight of the resin, will definitely enhance the resistance of the resin to discoloration and other deterioration by light. Increasing quantities, up to about 8%, will give still further enhanced stability. For most practical purposes, from 2 to 7% will provide an adequate degree of protection. Still greater quantities up to 20% may be employed, but will usually be found unnecessary and waste-. ful. All of the foregoing percentages are given:

on the basis of the weight of the resin.

With the foregoing general discussion in mind,- there are given herewith detailed examples of the, practice of this invention. All parts given are by;

weight.

EXAMPLE A. Preparation of bisphenoZ-A salicylic acidi reaction product The above ingredients were charged into a reac-- tion vessel provided with a heating jacket and a. reflux condenser. The vessel was heated until refluxing commenced, which refluxing was continued for 15 hours. At the end of this time, the reaction mass was cooled to room temperature, and washed successively with deionized water, 5 aqueous sodium hydroxide solution, and again with deionized water. The mass was then dried over anhydrous sodium sulfate, and distilled to remove the solvent, leaving a product which was a sticky, viscous, clear, amber-colored liquid.

liquid was then subjected to molecular distillation, and fractions taken at temperatures 7 and pressures as indicated hereinafter in Table I.

B. Preparation of 2,3-dichloro-L3- butadiene polymers MP-189 .81 manufactured by E. I. du Pont de lt enmufrs1 69: 00.16

ion 0 to carbon-atom parafiins under ex osure to ultraviolet light. Free of electrolytes. p

The above ingredients were charged under.

anaerobic conditions into a polymerization vessel and agitated at 30-4=0 C. for 24 hours. I The resultant-latex was coagulated by addition of mem Sodium salts of the products of sulfonaate mee anole thecoagu-lu'm "dewateredby: filtratiom: washed with waterorr the filter, and-dried; The

resultant pulverulent resin-was employed as a base resin --for--- stabilization-- tests as described 8-1 bulb consists. of :a combination tungstenffil' ment and mercury are enclosed :in a :zCOrex;

glass envelope whichabsorbsrmost'of the ultrahereinafter. Thisresin had-an intrinsic viscosvioletradiation below 280o -zzi. Thexbulb isgratedr y;.' u m 'ortho dichlorobenzeneatat 400' Watts-andoperatingvoltage is maintained... 0 '-0- at 100:2 volts.

C. Preparation-:of. stabilization test specimena The! F lsillrovld'edtclrt'ular pl turntableel'ii inches in diameter revolving at '15 R. P.1M-supon v Parts an -axisthrough'its center and perpendicularto Dwhlerobutadleee ff (Prepared itsplane. The lampis mounted-coaxiahy 'withi scnbed under B above) 100 said -axis;-wit-h the bottom of the-"bulb Winches f efrom'thecen-terof the turntable'.- The test spec-i- BlsphenolfA'saihcych'c'l'acld reactlon prodflctr men-s-are-mountedfiationrawhite circular card-" or fraction thereof prepared asdescribed 15%. board f fi i h thi ki d. .15' in h ti ediameteiw A 3 placed on the turntable concentric therewith. sahcylate of 2:4d1amy1 Phenol 5 The specimens (a large number are run simul- A series of stabilization tests was run, using the ta eously) are disp s radially p e a dreaction product of bisphenol-A and salicyclic boa d. w their Inner ds on a radius acid prepared as above described, or molecular inches from the center thereof. A circular cover distillation fraction thereof as set forth in Table I ard 4 /4 c s n di m t is m u t d n t p hereinafter. In each test, the reaction product. of the specimens concentric with the turntable 2,4-diamyl phenyl salicylate and the acetone so as to cover the innermost half of the speciwere dissolved together, the dichlorobutadiene r mens. polymer was added to the solution and the entire t h e d of the periods of CXDOSUI'e 0 t e mixture was thoroughly worked together. The test specimens, they were removed and subjecmixture was then spread out into a thin layer tively rated as to color by comparison with a and freed of the acetone by application of gentle series of standard colored specimens ranging heat. The salicylate was included as a plasti- 30 from water-white to dark brown and arbitrarily cizer, as it has no great stabilizing action. rated from O for water-white to 10 for dark brown.

One-half gram of the blended resin, stabilizer Following are the results of these tests.

Table I T Wt f Stability Test Color RatingAfter Out g Pressure C 1 St t (110ml) (p l ts) 0M a e 48 72 96 120 144 185 hrs. hrs. hrs. hrs. hrs. hrs.

original reaction product before distillation 0 0+ 1 1 2 3 110 30 23 light yellow 0 0+ 1 1 2 a 110 15.3 do 0 0+ 1 1 2 3 120 12 35.5 low. 0 0+ 1 l 2 3 130 13 25.1 dark yellow 0 0+ 1 1 2 3 140 11 15.5 do 0 0+ 1 1 2 3 l50 l80 12 25.2 o an e 0 0+ 1 1 2 a 100 15 19.7 do 0 0+ 1 1 2 s 200 14 16.6 do 0 0+ 1 1 2 a 210 12 19.5 -do 0 0+ 1 1 2 3 220 13 28.9 d0 0 0+ 1 1 2 a 230 25 16 light orange 0 0+ 1 1 2 3 and plasticizer was poured onto a sheet of aluminum foil to form a conical pile, a second sheet of aluminum foil placed on the pile to cover the same, and the assembly placed in a laboratory press having flat parallel platens heated to 180 C. The platens were quickly closed on the assembly, and left in light contact therewith for 10 seconds, after which a total load of 2460 pounds was applied to the platens and maintained for seconds. The press was then quickly opened, the assembly removed and quenched in cold water and the foil sheets peeled 011 from the resultant fused plaque (usually about .005 inch thick) of resin and stabilizer. From this plaque were cut test specimens 2 inches long and .25 inch wide, which were subjected for varying periods of time to a light aging test as described below.

EXPOSURE OF TEST SPECIMENS The test specimens prepared as above described were then subjected to exposure for various periods of time in a test substantially identical with the A. S. T. M. test D620-T. For this test there is provided a General Electric sunlamp, Model BM12 equipped with a reflector approximately 15 inches in diameter at the lower rim, with a General Electric 8-} bulb which has been in operation It will be seen that all of the fractions, as well as the original undistilled reaction product, had substantially identical, and very excellent, stabilizing effect in the dichlorobutadiene resin. The reaction product is not readily amenable to analysis or elucidation, but appears to consist principally of the monoand di-salicylates of bisphenol-A.

From the foregoing general discussion and detailed specific examples, it will be evident that this invention provides a novel and highly effective agent for stabilizing the dichlorobutadiene resins. The stabilizer of this invention may readily be synthesized from cheaply and readily procurable starting materials, and entails no special difficulties in compounding and use. The stabilizer is non-toxic and, so far as has been observed, has no irritating effect on the skin.

What is claimed is:

1. A light-stable composition of matter comprising (A) a resin selected from the group consisting of polymers of 2,3-dichloro-1,3-butadiene and copolymers thereof with other unsaturated compounds copolymerizable therewith containing at least 25% of 2,3-dichloro-1,3-butadiene copolymerized therein, together with (B) from 0.5% to 20%, based on the Weight of said resin.

7 of the product of reaction, uiidei esterifying conditions, of bisphenoi-A and salicyclic acid.

2. A light-stable composition of matter comprising a polymer of 2,3-dichloro-1,3-butadiene having an intrinsic viscosity from 0.1 to 1.5, together with from 0.5% to- 20%, based on the weight of said polymer, of the product of reaction, under esterifying conditions, of bisphenol-A and salicylic acid.

3. A light-stable composition of matter comprising (A) a resin selected from the group consisting of polymers of 2,3-dichloro-1,3-butadiene and copolymers thereof with other-unsaturated compounds copolymerizable therewith containing at least 25%0f 2,3-dich1oro-1,3-butadiene copolymerized therein, together with (B) from 6.5 to 20%, based on the weight of said resin, of hisphenol-A monosalicylate.

4. A light-stable composition of matter comprising (A) a resin selected from the group consisting of polymers of 2,3-dich1oro-l,3-butadiene and copolymers thereof with other unsaturated compounds copolymerizable therewith containing at least 25% of 2,3-dichloro-1,3-butadiene copolymerized therein, together with (B) from 0.5 to 20%, based on the weight of said resin, of hisphenol-A disalicylate.

EUGENE P. STEFL. LLOYD O. BENTZ.

No references cited. 

1. A LIGHT-STABLE COMPOSITION OF MATTER COMPRISING (A) A RESIN SELECTED FROM THE GROUP CONSISTING OF POLYMERS OF 2,3-DICHLORO-1,3-BUTADIENE AND COPOLYMERS THEREOF WITH OTHER UNSATURATED COMPOUNDS COPOLYMERIZABLE THEREWITH CONTAINING AT LEAST 25% OF 2,3-DICHLORO-1,3-BUTADIENE COPOLYMERIZED THEREIN, TOGETHER WITH (B) FROM 0.5% TO 20%, BASED ON THE WEIGHT OF SAID RESIN. OF THE PRODUCT OF REACTION, UNDER ESTERIFYING CONDITIONS, OF BISPHENOL-A AND SALICYCLIC ACID. 